@article {6952, title = {Agreement between circulating IGF-I, IGFBP-1 and IGFBP-3 levels measured by current assays versus unavailable assays previously used in epidemiological studies.}, journal = {Growth Horm IGF Res}, volume = {26}, year = {2016}, month = {2016 Feb}, pages = {11-6}, abstract = {

OBJECTIVE: Levels of insulin-like growth factor (IGF) proteins are associated with the risk of cancer and mortality. IGF assays produced by Diagnostic Systems Laboratories (DSL) were widely used in epidemiological studies, were not calibrated against recommended standards and are no longer commercially available.

DESIGN: In a split sample study among 1471 adults participating in the Cardiovascular Health Study, we compared values obtained using DSL assays with alternative assays for serum IGF-I (Immunodiagnostic Systems, IDS), IGFBP-1 (American Laboratory Products Company, ALPCO) and IGFBP-3 (IDS).

RESULTS: Results were compared using kernel density estimation plots, quartile analysis with weighted kappa statistics and linear regression models to assess the concordance of data from the different assays. Participants had a mean age of 77years. Results between alternative assays were strongly correlated (IGF-I, r=0.93 for DSL versus IDS; log-IGFBP-1, r=0.90 for DSL versus ALPCO; IGFBP-3, r=0.92 for DSL versus IDS). Cross tabulations showed that participants were usually in the same quartile categories regardless of the assay used (overall agreement, 74\% for IGF-I, 64\% for IGFBP-1, 71\% for IGFBP-3). Weighted kappa also showed substantial agreement between assays (kw, 0.78 for IGF-I, 0.69 for IGFBP-1, 0.76 for IGFBP-3). Regressions of levels obtained with DSL assays (denoted X) to alternative assays were, IGF-I: 0.52X+15.2ng/ml, log-IGFBP-1: 1.01X-1.73ng/ml IGFBP-3: 0.87X+791.1ng/ml. Serum values of IGF-I, IGFBP-1 and IGFBP-3 measured using alternative assays are moderately correlated.

CONCLUSIONS: Care is needed in the interpretation of data sets involving IGF analytes if assay methodologies are not uniform.

}, issn = {1532-2238}, doi = {10.1016/j.ghir.2015.12.007}, author = {Aneke-Nash, Chino S and Dominguez-Islas, Clara and B{\r u}zkov{\'a}, Petra and Qi, Qibin and Xue, XiaoNan and Pollak, Michael and Strickler, Howard D and Kaplan, Robert C} } @article {7258, title = {Insulinlike growth factor binding protein-1 and ghrelin predict health outcomes among older adults: CHS cohort.}, journal = {J Clin Endocrinol Metab}, year = {2016}, month = {2016 Nov 07}, pages = {jc20162779}, abstract = {

CONTEXT: Multiple diseases may explain the association of the growth hormone / insulinlike growth factor-I (GH/IGF-I) axis with longevity.

OBJECTIVE: To relate circulating GH/IGF-I system protein levels with major health events.

DESIGN: Cohort study Setting: Four US communities Participants: Adults (n=2268) 65 years and older free of diabetes and cardiovascular disease.

MEASUREMENTS: We assessed insulinlike growth factor binding protein-1 (IGFBP-1) and ghrelin in fasting and 2-hour oral glucose tolerance test (OGTT) blood samples, as well as fasting IGF-I and IGFBP-3. Hazard ratios for mortality and a composite outcome for first incident myocardial infarction, stroke, heart failure, hip fracture, or death were adjusted for sociodemographic, behavioral, and physiologic covariates.

RESULTS: During 13,930 person-years of follow-up, 48.1\% individuals sustained one or more components of the composite outcome and 31.8\% died. Versus the lowest quartiles, the highest quartiles of fasting and 2-h ghrelin were associated with a 27\% higher (95\% CI: 6\%, 53\%) and 39\% higher (95\% CI: 14\%, 71\%) risks of the composite outcome, respectively. The highest quartile of 2-h IGFBP-1 was associated with 35\% higher (95\% CI: 1\%, 52\%) risk of the composite endpoint. Similarly, higher mortality was significantly associated with higher fasting and 2-h ghrelin level, and with 2-h IGFBP-1 level. When examined together, 2-h post-OGTT levels of IGFBP-1 and ghrelin tended to predict outcomes better than fasting levels.

CONCLUSIONS: Circulating IGFBP-1 and ghrelin measured during an OGTT predict major health events and death in older adults, which may explain the influence of the GH-IGF-axis on lifespan and health.

}, issn = {1945-7197}, doi = {10.1210/jc.2016-2779}, author = {Kaplan, Robert C and Strizich, Garrett and Aneke-Nash, Chino and Dominguez-Islas, Clara and B{\r u}zkov{\'a}, Petra and Strickler, Howard and Rohan, Thomas and Pollak, Michael and Kuller, Lewis and Kizer, Jorge R and Cappola, Anne and Li, Christopher I and Psaty, Bruce M and Newman, Anne} }